Update nginxinc/nginx-unprivileged Docker tag to v1.27 (#39)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Dockerfile

@@ -13,7 +13,7 @@ COPY --chown=1001:root . .
 RUN chmod +x prepare_theme.sh && ./prepare_theme.sh
 RUN mkdocs build
 
-FROM nginxinc/nginx-unprivileged:1.26-alpine as deploy
+FROM nginxinc/nginx-unprivileged:1.27-alpine as deploy
 COPY --from=builder $HOME/application/site/ /usr/share/nginx/html/oaas/
 COPY default.conf /etc/nginx/conf.d/